ccDan - 8:50 pm on Mar 20, 2007 (gmt 0)

I'd avoid proprietary viewers. If they are not cross-platform, you will limit your potential audience. If they are not printable, you will annoy your audience.

I'd go with PDF. Just make sure you use a font that you can embed in the document. I've seen a number of eBooks where the font was not embedded and Acrobat had to use font substitution, and then the text may not align and space properly.

And, there's nothing worse than an eBook you cannot print. If the eBook is something useful, I'll print and bind it for easier reading and reference. Only eBooks of little value (or too large) don't get printed out.

Besides, no matter what you put it into, if a person can read it, they can duplicate it. You can't completely prevent someone from copying and reproducing your eBook--you can only make it more difficult for them to do. But, you should avoid doing that in such a way that hinders your readers' use of the eBook.